formula.expert

Constants library

2 values, each with its units, its uncertainty, and where it came from.

Electromagnetic 2

Josephson constant exact

KJ=4.835978484169836×1014 Hz/VK_{\mathrm{J}} = 4.835978484169836 \times 10^{14}\ \text{Hz/V}

Hz/VThe frequency-to-voltage ratio 2e/h of a Josephson junction — 483.6 THz per volt, and the modern practical realisation of the volt.

von Klitzing constant exact

RK=25812.8074593045 ΩR_{\mathrm{K}} = 25812.8074593045\ \text{Ω}

ΩThe quantum Hall resistance h/e² ≈ 25.813 kΩ, exact since 2019 and the reference by which the ohm is now realised worldwide.